Hi Jeff,
Thanks for the interest in our plugins. I can answer your questions.
Is Community Events or Eventbrite Tickets capable of calculating the total amount of participants in an event?
Community Events does not have this feature.
Eventbrite still handles all the tickets so in the Eventbrite settings for that event all that information is there.
Also, is it possible for the participants to have their own user WordPress login to sign up for the event?
For the Eventbrite Add On they still handle all the ticket sales so the account is actually created with Eventbrite.
If you used one of our ticketing plugins such as WooCommerce Tickets that handles the sales itself and can use WordPress accounts for the checkout information. That plugin also has a attendee list per event.
Let me know if you have any follow up questions.
Thanks